Commercial tomato products increasingly employ diced tomatoes, since diced tomatoes provide tomato particulates and flavor to such products. It is known that the firmness of the diced tomato particulates can be enhanced by the addition of calcium through adding calcium chloride. It is known to add the calcium chloride directly as a pre-weighed quantity or as part of the tomato topping juice for the diced tomatoes to maintain control of the calcium concentration of the finished product within legal constraints.
Typically, diced tomatoes are filled into a can and the calcified juice/puree is added, after which the cans are seamed and heat processed. Alternatively, a measured quantity of calcium chloride is added to the can which has been filled with tomatoes and the topping juice. The can is then sealed and heat processed.
Eamons et al. U.S. Pat. No. 2,549,781 discloses a process for canning fruits and vegetables comprising placing a charge of NaCl in a can, filling the can with a fruit or vegetable, adding to the top of the material a measured amount of dry calcium chloride, closing the can and subjecting the contents to a cooking temperature.
IFT Institute of Food Technologists 1989 presentation entitled "Optimization of a Diced Tomato Calcification Process" by John D. Floros et al. indicated the feasibility and desirability of controlling tomato dice firmness through strict calcium control in a batch process wherein the calcium chloride is introduced in a calcium chloride aqueous solution. Floros et al. "Optimization of a Diced Tomato Calcification Process," J. Food Sci. 57 pp. 1144-1147 (1992) is said to be based on the IFT paper. The authors indicate that processing of diced tomatoes at a CaCl.sub.2 concentration of 0.43% for 3.5 minutes would yield a product with improved firmness.
While Floros et al. indicate the desirability of strict calcium control, they do not teach how the small laboratory batch process could be applied to a workable continuous production process. In particular, Floros et al. do not indicate how the solution containing calcium chloride which is recirculated could be quickly measured to determine the calcium chloride concentration and such concentration quickly readjusted to replace the calcium absorbed by the tomato dices.
Sewon U.S. Pat. No. 5,039,545 is directed to a brine for conserving cucumber in bulk, which is low in sodium chloride. The brine includes at least 0.1 g calcium chloride. It is said that the brine can be reused after addition of sodium chloride and calcium chloride and acid to compensate for chemicals absorbed by the cucumbers during conservation. The reusable brine is said to avoid the serious effluent problems of conventional brines due to their high chloride content.
Sewon U.S. Pat. No. 5,112,639 is based on a continuation-in-part application of Sewon U.S. Pat. No. 5,039,545 discussed above. The invention relates to a brine for conserving cucumbers in bulk which is low in sodium chloride and optionally sodium free. The sodium chloride content of the brine is lowered or even partly or completely replaced by calcium chloride, provided the content of ingestible acids such as acetic and lactic acids are simultaneously kept at a relatively high level.
Meyer et al. U.S. Pat. No. 4,109,314 is directed to a fruit analyzer for testing fruit and fruit juice samples to obtain automatically test data relating thereto and for using the data to compute and print out characteristic parameters. A computer controlled testing unit has a suspended plummet soluble solids testing means including plummet, weight and temperature transducers as well as an acid testing means including liquid weight and pH transducers for automatic titration of the contents. Various other parameters are said also to be computed. Fruit juice is transferred from the test vessels to a waste disposal.
Rosemount Analytical Model 1054A Series Microprocessor Analyzers brochures disclose that the model 1054As with the appropriate sensors are designed to continuously measure conductivity, percent concentration and residual chlorine of industrial processes. Calibration is said to be easily accomplished by immersing the sensor in a known solution and entering the value. Measurement of 0 to 15% CaCl.sub.2 is mentioned. However, nothing is said about measurement of CaCl.sub.2 in complex solutions such as tomato juice.